The physiologic aspects of flight impart unique stresses to the patient. The most obvious change is the decrease in ambient pressure to a typical altitude equivalent of 6,000 to 8,000 feet during long-range transport. Aircraft cabin altitude can be maintained near sea level, but this increases fuel consumption and limits aircraft range. Considerations for mechanical ventilation during long-range air transport have been reviewed . Gas volume increases by a factor of 1.35 between sea level and 8,000 feet, so careful attention must be paid to trapped gas within the patient and within medical devices. Contraindications to air transport at reduced ambient pressure include decompression sickness and gas trapped in the thorax, pericardium, bowel, eye, or skull unless these conditions are specifically addressed. Gas expansion in an endotracheal tube cuff increases pressure on the tracheal mucosa, so air should be replaced with sterile saline or cuff pressure should be monitored and adjusted frequently during the transport. In spontaneously breathing patients, decreased partial pressure of oxygen is reflected in decreased arterial oxygen saturation unless oxygen supplementation is increased. The effect in mechanically ventilated patients is less obvious, likely due to the effectiveness of positive-end expiratory pressure in a hypobaric environment . It has been the experience of CCATTs that nearly all patients with acute respiratory distress syndrome can be adequately oxygenated during long-range air transport while following a lung-protective strategy. The low humidity experienced during air transport causes increased insensible fluid loss in patients and caregivers. Patients with burns and tracheotomies as well as children and neonates are particularly susceptible to drying, so this must be accounted for in their care.
The expansion of ICU facilities during the SARS epidemic in Hong Kong and Singapore was recently described . Infection control is recognised as an overriding priority for the delivery of criticalcare, including the ability, in the early stages, to cohort cases. This should ideally include the use of separate entrances and exits, isolation rooms with negative pressure ventilation and dedicated separate healthcare staff. The Toronto experience identified 21 secondary cases of nosocomial transmission of SARS in ICU from an initial index case before infection control measures were introduced. Even following the introduction of extensive protective equipment, nine healthcare workers developed SARS as a result of being present in the room during the intubation of a single patient. In terms of personal protection, planning and practice in the donning of protective equipment (PPE) and prior fit testing is essential . The practicalities of being able to manage patients when fully attired must be understood and consideration given to the fact that any procedure or task will take longer. This will impact on care efficiency and the staff to patient ratio.
Other researchers (Puntillo and McAdam, 2006; Beckstrand, Callister and Kirchhoff, 2006) have stressed that open channels of communication among healthcare personnel will improve patient care, with team members working towards achieving the same goal. According to Beckstrand, Callister and Kirchhoff, (2006), for improved communication to occur, a change in criticalcare culture must be attained. The realization that curative care and end-of-life care can co-exist in the criticalcare setting can lead to improved communication among all professional groups (McCallum and McConigley, 2013). The findings of this review support these observations, where nurses emphasized the importance of effective communication among healthcare teams, and its influence on patient care. The need for advocacy often occurs in the criticalcare setting, where clinicians are confronted with ethically difficult care situations (McSteen and Peden-McAlpine, 2006). Nurses in this review reported the experience of ethically difficult care situations involving care of the dying. As previously stated, this situation becomes even more challenging when the patient is not able to make healthcare decisions. Gadow (1980) confirmed that when patients with cancer were faced with extremely difficult decisions that had to do with quality versus quantity of life, it was the nurse who was in a position to explain the treatment objectives, and clinical information that supplemented the subjective, personal information that only the patient could give. According to Gadow (1980), patients may conform if they are inexperienced in making healthcare decisions and are given no assistance in developing their autonomy. The role of the nurse as an advocate therefore, is to overcome initial inequality by assisting patients to self-determinism, rather than conform out of inexperience or difference (McCallum and McConigley, 2013; McSteen and Peden-McAlpine, 2006)
Critically ill patients frequently experience delirium , and therefore removal of one or more of the electrodes during the recording is a significant risk and the amount of sedation or antipsychotic therapy required in these patients may be increased by their presence. The support and financing of polysomnography in terms of sleep laboratory equipment and skilled staff, as well as the practical difficulties, have led investigators to adopt other techniques in criticalcare. Indeed, some studies have used portable polysomnographic equipment capable of providing simplified sleep character- istics such as total sleep time . Such methods may provide a more feasible approach to future polysomnography studies in criticalcare patients. Since the advent of digital polygraphic recording, there is probably less variation in recording equipment used and modern equipment is less cumbersome than previously. The technical difficulties of undertaking polysomnography in criticalcare patients are frequently highlighted [1,27,36,37,46]. However, fewer than half of the studies using polysomnography identified any practical difficulties or loss of data (Table 2), which suggests that there is under-reporting of these difficulties in research studies.
Organisations vary considerably in their capacity for clin- ical system improvement . In the Lilly et al. study , best practices for the prevention of venous thrombosis, car- diovascular complications, ventilator-associated pneumonia, and stress ulcers were standardised and ICU daily goal set- ting was introduced a year before the start of the study, im- plying that there was opportunity for quality improvement at this stage. In the Lilly et al. study , all the ICUs that took part were self-selected, based on a willingness to invest in care improvement. However, the starting points of care delivery systems in terms of information technology, service improvement practices, systems, and structures  were not reported. The intervention period for Lilly et al.  was 16 months which is relatively short given the nature of organisational and cultural change associated with imple- mentation of a complex intervention such as telemedicine.
In another study investigating the pathophysiology of SAE, Szatmári and colleagues assessed cerebrovascular reactivity using an acetazolamide challenge in SAE patients . In a prospective cohort, patients with clinical sepsis and disturbances of consciousness of any degree were studied. In addition, 20 age-matched and sex-matched controls without previous diseases aﬀ ecting cerebral vasoreactivity were also included. Transcranial Doppler blood ﬂ ow velocities were then measured at baseline and 5, 10, 15 and 20 minutes after intravenous administration of 15 mg/kg acetazolamide. Th e time course of the CBF velocity response to acetazolamide was measured and cerebrovascular reactivity was calculated (the percentage increase in the mean blood ﬂ ow velocity). In addition, the maximum vasodilatory eﬀ ect (cerebro- vascular reserve capacity) was determined. Th e authors found that the time course of the vasomotor reaction to acetazolamide was delayed and the maximal vasodilatory response was reduced in SAE patients. Th e authors propose that cerebral hemodynamic changes might be involved in early pathogenesis of SAE.
Observation in an ICU or similar setting is strongly recom- mended for at least the first 24 hours after ictus (Class I, Level of Evidence B), since the risk of neurological deteri- oration is highest during this period  and because the majority of patients with brain stem or cerebellar hemorrhage have depressed levels of consciousness requiring ventilatory support  (Figure 3). Measurements in the ICU indicated for the optimal cardiovascular monitoring of ICH patients include invasive arterial blood pressure, central venous pressure, and, if required, pulmonary artery catheter monitor- ing. An external ventricular drain should be placed in patients with a depressed level of consciousness (GCS score ≤8), signs of acute hydrocephalus or intracranial mass effect on CT, and a prognosis that warrants aggressive ICU care . Outcomes after ICH are better when patients are cared for in specialized ICUs. In a large administrative database, Diringer and colleagues  demonstrated that mortality after ICH was associated with lower GCS scores, higher age, and admission to a general medical-surgical, as opposed to specialty neurological, ICU. In this study a clear impact on outcomes was seen when patients were admitted and cared
The management of stress-related hyperglycemia has been the focus of several prospective studies that yielded results still fueling a hot debate [1,2]. The concept of the three domains of dysglycemia (hyperglycemia, hypoglycemia, and glycemic variability) has emerged over the last year. Indeed, all three domains have been independently associ- ated with increased risk of mortality in ICU patients [3,4]. Analysis of the results showed that hypoglycemia had the strongest association with mortality and that the negative effects of hyperglycemia and greater glycemic variability were additive. Nowadays, the magnitude of stress-related hyperglycemia can be considered a surrogate marker of the severity of disease. Hence, an optimal target of glucose control is probably elusive, and the quality of glucose control should rather be considered a quality indicator of criticalcare service. Those findings fostered research in several different fields. Epidemiological insights included association studies between blood glucose (BG) and out- come, endocrine pathways were investigated as potential contributors of stress hyperglycemia, and computer- assisted decision systems and continuous glucose moni- toring were assessed in clinical conditions.
Medical emergency teams are used to provide expert criticalcare services for clinical deterioration promptly in non-ICU wards. Th ere is a large variability in the roles of, composition of and services provided by these teams. Recent studies have questioned the impact of such teams on clinical outcomes . Implementation of medical emergency teams is a complex, multistep process, however, and it is thought that a large driver of the negative results in studies is associated with diﬃ culty in changing provider behavior and processes of care in hospital settings . Tobin and associates studied the impact of introduction of a medical emergency team on hospital mortality and evaluated individual hospital admissions over a 10-year period in 12 diﬀ erent hospitals in Australia . Th ey found that the beneﬁ t of medical emergency teams was delayed, and the beneﬁ t became apparent only after a medical emergency team had been active for more than 2 years in a hospital setting. After accounting for con founders, the mortality was not statistically diﬀ erent from that in the period before the medical emergency team in the ﬁ rst 2 years (OR = 0.99, 95% CI = 0.97 to 1.02), but hospital mortality decreased the longer the team had been in place in any institution (OR = 0.93, 95% CI = 0.91 to 0.96 for 2 to 4 years; and OR = 0.90, 95% CI = 0.88 to 0.92 where the system had been in place for more than 4 years). Similar to previously published data, this study again high lighted the fact that there is a large variation in the composition and role of the medical emergency teams. But more importantly the authors have shown that changes in outcomes associated with these teams took time to become apparent, but these improvements persist once hospital processes and culture are changed.
We summarize all original research in the field of criticalcare nephrology published in 2004 or accepted for publication in CriticalCare and, when considered relevant or directly linked to this research, in other journals. Articles were grouped into four categories to facilitate a rapid overview. First, regarding the definition of acute renal failure (ARF), the RIFLE criteria (risk, injury, failure, loss, ESKD [end-stage kidney disease]) for diagnosis of ARF were defined by the Acute Dialysis Quality Initiative workgroup and applied in clinical practice by some authors. The second category is acid–base disorders in ARF; the Stewart– Figge quantitative approach to acidosis in critically ill patients has been utilized by two groups of researchers, with similar results but different conclusions. In the third category – blood markers during ARF – cystatin C as an early marker of ARF and procalcitonin as a sepsis marker during continuous venovenous haemofiltration were examined. Finally, in the extracorporeal treatment of ARF, the ability of two types of high cutoff haemofilters to influence blood levels of middle- and high-molecular-weight toxins showed promise.
Burn-associated and contrast-induced acute kidney injury Continuing along the path of AKI pathogenesis, it must be remarked, once again, that critically ill patients undergo different types of AKI and that it is very im- portant to recognize exact AKI etiology in order to optimize its management . A particularly interesting and rather overlooked form of renal dysfunction is that occurring in severely burned patients . An important difference for burn-associated AKI is the intensity and duration of the inflammatory response, which may be persistent, especially when a significant portion of total burned surface area (namely >30%) is present . Septic renal dysfunction, multiorgan failure and thrombogenic factors are considered risk factors for direct renal paren- chymal damage in severely burned patients . Typic- ally, proteinuria occurs in burned patients, mirroring a clinical and subclinical glomerular and tubular damage . Hu and coworkers interestingly analyzed a retro- spective cohort of 396 severely burned patients; of these, 68.43% had proteinuria and more than one-half of them met AKI criteria . Remarkably, no patient without proteinuria developed AKI. In the light of this study, the amount of protein loss in urine not only seemed a clear index of clinical and subclinical renal injury, but was also proportional to ICU mortality. This study suggests that proteinuria should be used for identifying burn pa- tients at risk of developing AKI and those with worse prognosis.
criticalcare echocardiography who used the pocket ultrasound and a fully featured device (CX50, Philips Healthcare, Eindhoven, The Netherlands). There was good concordance in LVEF estimation between the two echocardiographic devices, but clinical assessment of LVEF poorly correlated with echocardiographic assess- ment. Altogether, these data emphasize that clinical as- sessment of heart function is far from reliable and that pocket ultrasound devices can now be considered as a new stethoscope. Minimal training is needed; emergency physicians following a web-based learning module and 3 hours of proctored practical training showed a good concordance with an experienced cardiologist for fo- cused echocardiographic examination .
human intervention, ‘closed loop’ ventilation may accel- erate liberation from mechanical ventilation. Data sup- porting clinical benefit are lacking and a randomized trial of closed loop control of pressure support ventila- tion failed to show a reduction in duration of ventilation . Nevertheless, this area of research is in its infancy, and most reports focus on establishing the feasibility and safety of closed loop systems in various populations. Adaptive support ventilation (ASV) is a ‘semi-automatic’ mode that adjusts driving pressure to achieve a set mi- nute ventilation by some optimal combination of tidal volume and respiratory rate determined based on the time constant of the respiratory system . Fully automatic ‘closed loop’ ASV automatically adjusts the target minute ventilation, PEEP and F i O 2 based on the
Progress in specific treatments for ARDS beyond lung- protective strategies of mechanical ventilation and conser- vative fluid management has not yet been realized. To develop novel therapies, we need to improve our ability to define appropriate molecular targets for preclinical devel- opment and, using relevant animal models and human models, develop better methods to determine the clinical value of novel ARDS agents. Clinical trials must have meaningful endpoints and use the available observational and meta-analytic data to inform design. Biomarker- driven studies or defined ARDS subsets should be consid- ered to categorize specific ‘at risk’ populations most likely to benefit from a new treatment. These innovations have been evident in the past year in respiratory criticalcare re- search, in laboratory studies, in observational research that attempts to better define diagnosis and prognosis, in inter- ventions aimed at defining further benefit that can be gained from protective lung ventilation strategies, and in the evaluation of new therapies for the treatment of this devastating syndrome.
Despite intense experimental and clinical research activ- ity over the past decades, sepsis still remains an elusive syndrome. Actual understanding has led to international recommendations on diagnosis and treatment , but management of severe sepsis and septic shock in the ICU still represents a major challenge for clinicians in 2014, with high mortality rates. The past year’s contribu- tion to the field of sepsis research was quite prolific, and the aim of this review is to summarise the relevant find- ings of research articles that were published in 2013 in CriticalCare and other relevant journals. We focus on advances in the understanding of sepsis physiopathology, diagnostic and prognostic biomarkers, potential new therapies, and epidemiologic and outcome studies.
Acute kidney injury (AKI) is a common and severe com- plication of critical illness associated with death and dis- ability. The symptoms and clinical consequences of AKI can be quite similar regardless of whether the etiology is predominantly within the kidney or predominantly out- side the kidney; the AKI syndrome encompasses both structural injury as well as acute functional impairment. The costs of care for these patients are very high and research on AKI is thus focusing on prevention, early detection and treatment. The non-profit foundation Kidney Disease: Improving Global Outcome (KDIGO), managed by the National Kidney Foundation with the aim of developing and implementing guidelines, com- pleted in 2012 the first international, multidisciplinary, clinical practice guidelines for AKI [1,2]. This workgroup utilized previously existing criteria to try and unify and develop all aspects, both clarified and uncertain, of AKI and criticalcare nephrology. The Acute Dialysis Quality Initiative group had designed the RIFLE (Risk, Injury, Failure, Loss of function and End-stage kidney disease) system for diagnosis and classification through a broad consensus of experts back in 2004 . This classification was also modified for pediatric patients in order to bet- ter classify small children with AKI (pediatric RIFLE) . More recently, the Acute Kidney Injury Network
Criticalcare medicine is a global specialty and epidemiologic research among countries provides important data on availability of criticalcare resources, best practices, and alternative options for delivery of care. Understanding the diversity across healthcare systems allows us to explore that rich variability and understand better the nature of delivery systems and their impact on outcomes. However, because the delivery of ICU services is complex (for example, interplay of bed availability, cultural norms and population case-mix), the diversity among countries also creates challenges when interpreting and applying data. This complexity has profound infl uences on reported outcomes, often obscuring true diff erences. Future research should emphasize determination of resource data worldwide in order to understand current practices in diff erent countries; this will permit rational pandemic and disaster planning, allow comparisons of in-ICU processes of care, and facilitate addition of pre- and post-ICU patient data to better interpret outcomes.
Although the most obvious clinical abnormalities in ALI and ARDS are referable to the lung, the most common cause of death is dysfunction of remote organs. In a single, medical- surgical intensive care unit (ICU), Flaatten and coworkers  identified 529 out of 832 adult patients with acute respiratory failure (ARF) without (n = 156) and with (n = 373) remote organ failure over 2.5 years. ICU, hospital, and 90-day mortality were 3.2%, 14.7% and 21.8 % in ARF without remote organ dysfunction, 67.6%, 69.6% and 82.1% in ARF with failure of three additional organs, and 30.0%, 40.5% and 46.9% in ARF with any remote organ dysfunction, respectively. The authors concluded that ARF without other organ failure has a comparatively low mortality rate, whereas ARF mortality rates increase with the number of concomitantly failing organs. The inert gas re-breathing technique does not measure trapped air within the lungs and may, therefore, under- estimate total lung gas volume. To assess the volume of poorly or non-ventilated gas, Rylander and coworkers  compared end-expiratory lung volume determined by re- breathing sulphur hexafluoride (EELV SF6 ), and total lung gas
reproduction attempts is also likely an important determin- ant of consistency, in that as more reproduction attempts are conducted, the likelihood of obtaining a result that dif- fers from the original study increases. The optimal number of reproduction attempts is not clear. When the first reproduction attempt reports findings consistent with the original study, this is likely adequate to assess the efficacy of a given clinical practice, especially if there are no signals from secondary analyses that additional patient subgroups and/or outcomes should be examined. In this case, additional reproduction attempts may result in patients not receiving beneficial practices (or unnecessarily experi- encing ineffective practices), and waste of valuable health- care and scientific resources. When the findings from a first reproduction attempt are not consistent with the original study, clinicians and scientists should view that in- consistency as an opportunity to pause and re-examine each component of the clinical question (i.e., population, intervention, etc.) before moving forward with any additional experimental research. Additional understand- ing pertaining to rates and predictors of reproducibility will help scientists decide which practices warrant repeat exam- ination through a reproduction attempt, and may help de- sign studies that are less susceptible to non-reproducibility. Similarly, funding agencies may be better positioned to weigh the relative importance and methodological strength of a proposed reproduction attempt, which may help in- form the controversial balance between funding science that intends to examine existing concepts and science that intends to discover new concepts.
The limitation of the current data is that they are confined to case reports and series with no prospective, systematic investigations in the intensive care unit available. Positive outcome bias is the concern with this retrospective data. The more extensive thoracic anaesthesia experience suggests that despite its potential complications, OLV can be safely instituted on a short term basis. There is also evidence to show that gas exchange and ventilatory targets can be met with ILV. Outcome and mortality data are lacking, however, and this remains an area for future clinical research.